Receivables From and Payables to Brokers, Dealers, and Clearing Organizations (Amounts Payable to Brokers, Dealers, and Clearing Organizations) (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Due to and from Broker-Dealers and Clearing Organizations [Abstract]
Deposits received from securities loaned	$ 500,104	$ 252,137
Securities failed to receive	108,632	30,906
Payable to clearing organizations	105,401	20,335
Total payables to brokers, dealers, and clearing organizations	$ 714,137	$ 303,378

Amount payable to other broker-dealer and clearing organization, including, but not limited to, security failed-to-receive, deposit received for security loaned, open transaction, and floor-brokerage payable.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Rule 15c3-1
-Number 240
-Section 15c3-1
-Publisher SEC

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 940
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481833/940-20-45-3

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- Definition

Amount payable to broker-dealers or clearing organizations for executing or clearing trades or orders.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(24))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 940
-SubTopic 20
-Name Accounting Standards Codification
-Section 25
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481913/940-20-25-2

+ Details

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- Definition

Amount of obligation to return cash received as collateral for security loaned to another party.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-04(11))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479170/946-210-S99-1

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- References

No definition available.

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- Definition

Amount payable as the result of fail-to-receive. A fail-to-receive is a securities purchase from another broker-dealer not received from the selling broker-dealer by the close of business on the settlement date.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 940
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481833/940-20-45-3

+ Details

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